Air neutralization

ABSTRACT

A gas such as common air may be treated so as to be electrically &#39;&#39;&#39;&#39;neutralized&#39;&#39;&#39;&#39; by passing the gas through the space between charged electrodes. These electrodes are changed by an AC current having a sinusiodal wave form which creates a field having an intensity in the space of at least 8 microamps per square inch. The gas being treated is passed through this space at a rate such that the gas is between the electrodes during a complete cycle of the AC current or during an even multiple of such a complete cycle. As the gas passes through the electrodes, various charges carried by or within the gas are removed from it.

United States Patent Fischer [54] AIR NEUTRALIZATION [72] Inventor:Ronald S. Fischer, 4636 N. Pick Road, El

Monte, Calif. 91735 22 Filed: Feb .9, 1971 [21] Appl. No.: 1 13,929

[52] U.S.Cl ..3l7/262 AE,21/53,21/54 R, 2l/74R,21/l02R,l19/l5 [51] Int.Cl ..A61l 1/00, A611 9/00 [58] Field ofSearch; ..317/262 AE; 128/404,421; 204/164, 312; 119/15; 21/54 R, 102 R, 53

[56] References Cited UNITED STATES PATENTS 1,388,112 8/1921 Hoofnagle,.204/3l2 [151 3,654,534 [451 Apr. 4, 1972 1,934,704 1 H1933 Golden..317/262 AE Primary Examiner-L. T. Hix AttorneyEdward D. O'Brien 57]ABSTRACT A gas such as common air may be treated so as to beelectrically neutralized by passing the gas through the space betweencharged electrodes. These electrodes are changed by an AC current havinga sinusiodal wave form which creates a field having an intensity In thespace of at least 8 microamps 6 Claims, 5 Drawing F igurcs PatentedApril 4, 1972 3,654,534

FIG. 5, INVENTOR 52 50 46 RONALD 5. F/SCHER 0-4o 5y TRANSFORMER 50EDWARD D. OER/AM BACKGROUND OF THE INVENTION The present inventionrelates to the treatment of a gas such as common air so as toneutralize" the gas being treated.

Such neutralization involves a number of comparatively com- -cal chargesas the result of a number of natural and artificial phenomena. Suchcharges may be in the form of ions and/or free electrons in the air.They may also be present in the form of charged particulate matter suchas dust particles, bacteria, fungus spores, and the like. Frequentlysuch particulate matter will be held in the air so that it does notreadily settle out because of mechanisms such as Brownian movement,convection currents and the like. It is believed that the charges onsuch particles frequently prevent these particles settling out.

The positive and negative electrical charges in a gas may be equal sothat the gas as a whole will be electrically neutral or uncharged, butstill the gas will tend to behave as positively or negatively charged.This may happen under, a number of different circumstances. It may bethe result of the way charges are held on gas molecules, particularlylarge molecules, or the way charges are disposed on a particulate itemof particulate matter or the like. Many different particles which may beelectrically neutral in an absolute sense behave as and are referred toas charged particles because of the unbalanced way electrical chargesare located in or on such particles.

A recognition of these factors has led to the development of a number ofdifferent treatment procedures for electrically treating gases such asair so as to purify such gases. Probably most frequently such priorprocedures have involved merely passing a gas such as air betweenoppositely charged electrodes. Such electrodes are normally used with asufficient current to set up fields which attract electrical charges orcharged particles to the individual electrodes where there may be sometendency towards neutralization. Apparatus of this general typefrequently involves the use of an electrical discharge for use inremoving particulate material.

Procedures as are briefly indicated in the preceding paragraph arewidely considered to be reasonably effective in purifying" gases such asair by removing certain types of charges and charged particles from suchgases. Procedures such as are indicated are also effective in purifyingair by virtue of the fact that such procedures cause or promote certainchemical reactions having what can be a beneficial effect. Thus,procedures such as are indicated can be and frequently have been carriedout under such conditions as to promote the production of ozone fromoxygen within the space between the electrodes.

The highly reactive characteristics of ozone makes this gas highlydesirable in oxidizing many common impurities such as may be present inair. However, the production of ozone can also be extremelydisadvantageous inasmuch as such ozone emanating from an air treatmentapparatus as described may cause many undesired reactions such as dyefading and the like. Also to many the smell of oxone is somewhatobjectionable. It is understood that the effects of significantquantities of oxone on the human body are not completely understood.

The various different procedures indicated in the preceding discussionfor electrically treating gases such as air so as to purify such gaseshave been sufiiciently successful to indicate that electrical treatmentof gases such as air so as to neutralize various charges in such gasesis beneficial. It is also recognized that any such procedure to beacceptable in inhabited areas must be of such a character as to minimizeozone production. Although these things have been recognized it isconsidered that no one has adequately developed satisfactory proceduresfor electrically neutralizing a gas by passing such a gas in a fieldbetween charged electrodes.

SUMMARY OF THE INVENTION An objective of the present invention is toprovide a new and improved method and a new and improved apparatus forair neutralization. From this it will be apparent that a broad objectiveof the present invention is to provide for air neutralization of a typewhich overcomes defects and limitations of the prior art in this field.More specifically objectives of the invention are to provide foreffective air neutralization, efficient air neutralization and economicair neutralization.

These objectives standing by themselves in a sense do and in a sense donot indicate the purposes of the present invention. Simply stated one ofthe major purposes or objectives of the present invention is toeconomically clean-up gases such as air so as to make such air much moredesirable and so as to tend to remove from such air particulate matterwhich is either charged or which behaves substantially as if it ischarged. In accomplishing this the invention does not only operate uponthe inanimate content of air, but also operates upon living particlessuch as bacteria, fungus spores and the like found within air and othergases.

These objectives of the present invention are achieved by treating a gassuch as air by passing the gas through the space between spacedelectrodes to which an AC current is applied so as to create a fieldintensity in the space of at least 8 microamps per square inch. Inaccordance with this invention the gas is passed through this space at arate such that the gas is between the electrodes an amount of timecorresponding to a complete cycle of the AC current or during an evenmultiple of such a cycle. In other words, when the gas being treated iswithin the space between the electrodes it is not subjected to a partialAC cycle. It is considered necessary to use a structure as hereinafterindicated in order to accomplish this mode of operation over a prolongedperiod on an economic basis.

BRIEF DESCRIPTION OF THE DRAWING The nature of the present invention isbest explained in detail with reference to the accompanying drawing inwhich:

FIG. 1 is an isometric view of a presently preferred embodiment or formof an air neutralizer of the present invention;

FIG. 2 is a cross-sectional view taken at line 2-2 of FIG. 1;

FIG. 3 is a partial cross-sectional view taken at line 3-3 of FIG. 2;

FIG. 4 is a partial cross-sectional view taken at line 4-4 of FIG. 2;and

FIG. 5 is a schematic view indicating the connection of variouscomponents or parts within the air neutralizer shown.

It will be recognized that the accompanying drawing is primarilyintended for explanatory purposes in order to show the construction ofan air neutralizer in accordance with this invention. Those skilled inthe art of the construction and use of apparatuses for electricallytreating air and other gases will realize that various changes may bemade in the precise structure shown through the use or exercise ofroutine skill in this field without departing from the essentialprinciples of the invention as defined or summarized in the claimsforming a part of this specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing there isshown an air neutralizer 10 of the present invention. This neutralizer10 includes a generally rectilinear housing 12 having a hinged lid 14adapted to be opened in order to provide access to the interior of thehousing 12. At one end 16 of the housing 12 there is located a threesided frame 18 adapted to be closed by means of a small hinged lid 20 soas to retain in the end 16 a conventional air inlet filter pad 22 insuch a manner that this pad 22 may conveniently be replaced from time totime without opening the lid 14.

The interior of the frame 18 in back of the filter pad 22 is separatedfrom the interior of the housing 12 by means of another frame 24 whichholds across its center a conventional protective screen 26. A duct 38leads from the frame 24 to one end of an electrode assembly 30. Theconstruction of this electrode assembly 30 is best seen in FIGS. 2 and 4of the drawing. This assembly 30 includes a frame 32 of a conventionaldielectric material such as an acrylic polymer, a polyvinyl chloride orthe like. This frame 32 is directly connected to the duct 28.

It supports an aligned stack of a plurality of separate, parallel,identical glass plates 34 so that the adjacent side edges of theseplates 34 are spaced from one another by small spacers 36 and 37. Thespacers 36 are preferably of a conventional dielectric material such asa phenolic polymer; the spacers 37 are of a conductive metal such asbrass for a purpose as hereinafter indicated. The spacers 36 and 37, theplates 34 and the frame 32 are preferably secured together with a knownresilient dielectric material adhesive (not shown separately) such asknown silicone rubber polymer used on all of the abutting faces orsurfaces of these parts. Such an adhesive is considered preferable sinceit accommodates limited movement and shifting of the parts joined by itso as to increase the effective life of the neutralizer 10.

The construction and spacing of the plates 34 is considered to be quiteimportant in obtaining effective results with the invention and inproviding for long, effective utilization of the neutralizer 10. Thesefactors will be more fully explained hereinafter. The plates 34 carry ontheir surfaces inert, thin metal electrodes 38 which are in electricalcontact with the spacers 37. At the sides of the assembly 30 thesespacers 37 are connected together by conventional buss bars 40 so thatalternate electrodes at the sides of the assembly 30 are connected.

The electrodes 38 should preferably be closely adhered to the plates 34so that no air is trapped between these electrodes 38 and the plates 34in order to increase the length of time the neutralizer 10 may be usedwithout breakdown. Preferably the electrodes 38 are secured or adheredto the plates 34 by the use of a very thin layer of a bonding orcementing agent having a dielectric coefficient which is the same orwithin 10 percent of the dielectric coefficient of the plates 34. Thisis also considered so as to increase the length of time the neutralizer10 may be used without breakdown. It is considered that a suitablebonding and cementing agent is an equal part by weight mixture of beeswax and refined rosin.

During the operation of the neutralizer 10 a gas such as air beingtreated within this neutralizer 10 will be drawn into the housing 12through the filter pad 22, the duct 28 and the electrode assembly 30through the operation of a conventional blower 42. This blower 42 ismounted within the housing 12 so that it will pull gas through the partsindicated and then force or convey such gas outwardly through a smalloutlet 44. The performance of the blower 42 is considered quiteimportant to the invention as hereinafter indicated.

The power necessary to operate the neutralizer 10 is obtained through aconventional lead-in cord 46. It will be seen from an examination ofFIG. of the drawing that the power is supplied through a conventionalfuse 48, a conventional onoff switch 50 and a conventional interlockswitch 52 operated by the lid 14 so as to automatically shut off theneutralizer in the event that this lid 14 is opened. This power issupplied across the primary terminals of a transformer 54 mounted withinthe housing 12. The secondaries from this transformer 54 are connectedto the buss bars 40 through wires 52 so as to supply power to theelectrodes 38. Preferably, the motor 56 of the blower 42 is connected inparallel across the primary of the transformer 54. Also a conventionalneon lamp assembly consisting of a resistor 58 and a lamp envelope 60are also preferably connected in parallel across the primaries of thetransformer 54 in order to indicate when the complete neutralizer 10 isbeing operated.

During such operation of the neutralizer 10 the individual electrodes 38are supplied with AC power through the transformer 54. As theseelectrodes 38 are charged through the applied AC current, air or anyother gas being treated in the neutralizer 10 is drawn past theelectrodes 38 through the operation of the blower 42. As the air orother gas is moved in this manner it will, of course, be subjected tothe AC field between the electrodes 38 resulting from the applied power.With the present invention effective results coupled with prolonged,reliable performance of the neutralizer 10 require rather precise,careful control of the operation of the neutralizer l0 and ratherprecise control of the construction of this device. This can beillustrated by referring to any of a plurality of closely relatedfactors which are critical in one sense or another as far as theinvention is concerned.

Effective air neutralization in accordance with the invention requiresthat the gas being treated is moved between parallel leading andtrailing edges 62 and 64, respectively, of the electrodes 38 a period oftime such that any increment of such gas is subjected to a completecycle of an AC field or an even multiple of such a cycle, but not moreor less than such a cycle or multiple thereof. Any significant deviationfrom such a complete cycle is considered to be undesirably ineffectiveinasmuch as any such deviation does not subject a gas to equal positiveand negative fields. An unbalance between the positive and negativefields as applied to the gas passing between the electrodes 38 isconsidered to cause some residual charge to remain on or in the gasbeing treated.

The necessity with the invention of passing the gas being treatedthrough the space between the electrodes 38 at a rate such that the gasis between the electrodes 38 during a complete cycle of the applied ACcurrent or during an even multiple of such a cycle in effect dictates orgoverns several design parameters within the neutralizer 10. Thecapacity of the blower 42 used must be such as to move the gas beingtreated at the rate indicated under normal conditions of operation.Inasmuch as little if any significant advantage is considered to beachieved by using multiples of complete AC cycles in treatment inaccordance with this invention preferably the blower capacity is suchthat the gas treated is present between the electrodes 38 during only acomplete cycle of the applied AC current.

The time of such presence is related to the frequency of the appliedcurrent which should be used. If the frequency of the applied current isrelatively high for gas to be between the electrodes 38 for a period asindicated either (1) the gas velocity created by the blower 42 has to beso high as to cause mechanical problems in the operation of theneutralizer 10 such as problems of noise production or (2) the pathlength between the electrodes 38 has to be comparatively short. It isrelatively difficult to accurately make such a short length in a devicesuch as the neutralizer 10 correspond to a complete AC treatment cyclewith a conventional blower. In short, at high frequencies either the airneutralizer 10 becomes something of a wind tunnel or the electrodes 38become relatively short.

The undesirable consequences of using high frequencies are avoided inaccordance with the invention by utilizing frequencies of about cyclesper second or less. However, the frequency used should preferably be noless than about 30 cycles per second. In general if a lower frequencythan this is employed either (I) the length of the path taken by a gasin passing between the electrodes 38 has to be undesirably long or (2)the blower 42 used has to operate extremely slowly so that the gas willtraverse the electrodes at a very slow rate. If the electrodes arecomparatively long the neutralizer 10 is considered to take up morespace than reasonably necessary. If the blower 42 employed only movesthe gas very slowly, such a blower will tend to be inefficient in itsoperating characteristics and will normally not cause adequatecirculation of the gas being treated on the outside of the neutralizerl0. Particularly suitable results can be achieved using a frequency of60 cps.

The wave form of the AC voltage applied to the electrodes 38 isconsidered to be important in achieving desired results in accordancewith this invention. It is considered that the applied AC used inconnection with the electrodes 38 should have as reasonably close to apure sinusiodal wave form as it is possible to obtain. Although a puresinusiodal wave form is desired, it is considered that a closeapproximation of such a pure wave form will produce the desired resultswith this in-' vention. It is considered that an acceptable wave formwill not depart by more than 5 percent of the total harmonic shape of anAC sinusiodal wave. Such a wave shape is considered preferable since itenables a gas being treated with the neutralizer to be subjected to anelectrostatic field that changes at a uniform linear or constant rate.This is considered to minimize any tendency towards the creation ofelectrically unbalanced conditions in any gas treated in the neutralizer10.

These factors are also related to the intensity of the electrostaticfield created in the spaces in the assembly 30 traversed by a gas beingtreated. It is considered that if this electrostatic field is belowabout 8 microamps per square inch in intensity that the neutralizer willnot adequately neutralize charges in or charged particles in any gasbeing treated within it. The precise reasons for this are not known, butit is believed that such reasons pertain to the amount of energynecessary to radiate the gas treated so that charges may be readilyremoved from such gas. in other words, unless the field intensity is atleast 8 microamps per square inch the degree of neutralization achievedwith the invention is undesirably low.

On the other hand, if the field intensity is above about 12 microampsper square inch, a different type of problem is encountered with theinvention. In general, materials such are used in the construction ofthe assembly 30 and various parts of it will not withstand thecomparatively great dielectric stresses caused by field intensities ofthis level and above for prolonged periods. Since commercial and relatedeconomic reasons make it necessary that the neutralizer 10 operate forprolonged periods without breakdown, it is apparent that a fieldintensity above about 12 should not be used with the invention.Although, field intensities of from 8 to 12 microamps per square inchmay be used, it is presently considered preferable to utilize a fieldintensity of 10 microamps per square inch since this intensity workseffectively without significantly or noticeably causing deteriorationwithin the assembly 30.

It will be recognized that such field intensities are related to otherfactors by known mathematical relationships. One item which is relatedto the field intensities which can be used in the neutralizer l0concerns the dielectric materials between the electrodes 38 in theassembly 30. It will be recognized that there are two types ofdielectric materials between the electrodes 38: (l) the material withinthe plates 34 and (2) the material within the gas being treated.Normally the latter will be air.

The dielectric material in the plates 34 is preferably a conventionalisotropic dielectric material. Particularly, satisfactory results can beachieved using conventional soda glass. Anisotropic materials are notdesired for use with the plates 34 since such materials are apt tobreakdown after use for extended periods in the neutralizer 10, whereasisotropic materials will withstand prolonged use without significantbreakdown. The plates 34 should of course be of uniform physicalcharacteristics and thickness. They should have no surface imperfectionsand their edges should be polished so as to avoid edge effects. It isconsidered that the plates 34 should have a dielectric constant orcoefficient of at least five since with materials having a lowerdielectric constant than within this range, the voltage gradient whichwill appear across the plates 34 is sufficient to cause electricalstresses which will detrimentally effect the period of use of thedielectric without physical breakdown.

With the invention even the thickness of the plates 34 is considered tobe important. If these plates 34 are less than about 0.040 inches thick,it is considered that these plates are too fragile for practicalutilization. If on the other hand, these plates are thicker than about0.125 inches thick it is considered more material is used than isreasonably needed. The plates 34 should contain only enough dielectricmaterial in order to support the electrodes 38 used adequately withoutthere being danger of physical breakdown.

A factor which enters into the intensity of the electrostatic fieldobtained is of course the spacing between the plates 34 and theelectrodes 38-i.e. the air gap through which a gas flows in theneutralizer 10. It is considered that if this dimension is less thanabout one-thirty-second inch that the friction resulting from gas flowat the velocities necessary to obtain treatment as described isunnecessarily high. This, of course, raises the the performancerequirements for the blower 42. When there is such friction it isconsidered that power will be waisted as the result of physically movinga gas as described to obtain neutralization as herein indicated.

On the other hand, it is considered that if the spacing herein discussedis greater than about three-sixteenths inch, the voltage requirements atthe electrodes 38 necessary to achieve electrostatic fields of theintensity indicated become impractically large. As used in thispreceding sentence the term impractically relates to economicconsiderations as well as to factors such as size and weight. It isconsidered that preferred results are achieved using an electrodespacing of one-sixteenth inch. Gas will flow readily within a space thisthick and with such spacing the voltage requirement in the neutralizer10 does not become impractical.

The voltage gradients across both the plates 34 and the spaces betweenthe plates and the electrodes 38 are considered important in connectionwith the preceding parameters of the invention and in connection withachieving satisfactory operation. If the voltage gradient in the spacetraversed by the gas being treated is less than about volts per mil, itis considered that the neutralizer 10 will not operate satisfactorily.This is because with lesser voltage gradients it is considered that thegas being passed through the assembly 30 will not be adequately affectedso as to cause a desired degree of charged neutralization at the airflow rates used. On the other hand, it is considered that if a voltagegradient in the space traversed by the gas is greater than 100 volts permil that there is an unnecessary utilization of power. It is presentlypreferred to utilize a voltage gradient in the space traversed by thegas being treated of volts per mil since within this range adequateneutralization can be achieved without the unnecessary or uneconomicexpenditure of power.

The voltage gradient across the plates 34 used is critical in anotherregard. If the voltage gradient across these plates 34 is in excess of20 volts per mil, the electrical stresses set up in the plates 34 willtend to cause them to break down earlier than desired. In other words, avoltage gradient across the dielectric of over 20 volts per mil willtend to effect the duration of time the neutralizer 10 may be usedwithout break down. From this it will be apparent that the lower thevoltage gradient across the dielectric paltes 34, the lower the usefullike of the neutralizer 10 in service.

However, there is a practical lower limit as to the voltage gradientacross the plates 34 which can be employed. This limitation concerns thefield intensity in the space traversed by gas treated in the neutralizer10. There must be adequate power present within this space so as toobtain the desired neutralization. It is considered that normally thevoltage gradient across the plates 34 should not be less than 12 voltsper mil. Effective results without danger of premature break down cannotbe achieved with the voltage gradient across the plates 34 being morethan about 15 volts per mil.

From a careful consideration of the preceding it will be apparent thatall of the factors or parameters discussed relate to the total powerconsumption in a neutralizer as described.

Such power will also be determined or governed by other factors than arespecifically discussed in the preceding such as the number of the plates34 in the assembly 30, the dimensions of this assembly 30 and of theindividual parts of it and the like. Through routine calculations thepower to be consumed in a neutralizer such as the neutralizer 10designed in accordance with the preceding discussion can be readilydetermined. To facilitate an understanding of the invention it can beindicated that a neutralizer corresponding to the neutralizer 10 hasbeen operated satisfactorily utilizing a 60 cps. 5,000 rms. voltageoutput off of the secondary of a transformer as indicated at a totalpower level of about 1. 75 watts.

To a large extent the manner in which the neutralizer 10 serves to treata gas such as air and particles of various types carried by a gas willbe obvious from a careful consideration of the preceding portions ofthis specification. The neutralizer 10 is constructed so that any givenincrement or quantity of gas being treated is subjected to neither moreor less than a complete AC current cycle. Effectively any charges orparticles within the gas treated which tend to behave as cahrged will betreated in the neutralizer 10 so that there is an adequate opportunityfor charges or unbalanced charges to be discharged in the field created.

The field intensity used is adequate to accomplish this effect withoutsignificant or normally noticeable production of ozone. This isconsidered to be quite significant since ozone is relatively undesirablein many locations. One aspect of the present invention which isconsidered quite significant relates to the effectiveness of airneutralization as described in reducing the bacteria content of the airwithin an enclosed or relatively enclosed area without the use of ozoneto kill such bacteria.

It is known that after prolonged use of air neutralization as describedover a period of days in an area of a hospital, in a chicken house orthe like that the bacteria content in the area of such use issignificantly decreased. The effectiveness of air neutralization of thepresent invention in controlling bacteria content within a room isconsidered to evidence the unique character of the results achieved withthe present invention.

From studies of the morphology of typical bacteria it has been learnedthat in general such bacterias are electrically complex structures whichare electrically unbalanced in that positive and negative charges insuch bacteria are grouped in certain areas or regions. Because of thisit is considered that the air neutralization treatment describedinvolving subjecting bacteria to a complete AC cycle in a field of theintensity described tends to neutralize the unbalanced charges-that isthe groupings of segregated positive and negative chargeson bacteria insuch a way that after air neutralization as described such bacteria areeither inactivated or killed as a result of an electrically disrupted oraltered internal structure. However, the operation of the invention inthe control of bacteria and related micro-organisms does not appear torecognize that such micro-organsims go through an apparatus asdescribed. Airwithin a closed room which is circulated through anapparatus as indicated is neutralized so that it, the air, appears toremove or discharge charges or ions on bacteria or other relatedorganisms not going through the apparatus, which charges or ions arenecessary for their survival.

lCLAlM:

1. An apparatus for treating a gas so as to neutralize electric charges,which apparatus comprises:

treatment means including electrodes separated by a dielectric and anair space,

means for applying an AC current at a power level sufficient to create afield between said electrodes in said air space having an intensity ofat least 8 microamps per square inch, and

means for moving a gas through said air space at a rate such that thegas is moved between said electrodes so as to be subjected to said fieldfor a complete cycle of said AC current or an even multiple thereof.

2. An apparatus as claimed in claim 1 wherein:

said air space is from one thirty-second to three-sixteenths inch thick,

said AC current has a sinusiodal wave form of less than 5 percent totalharmonic, the frequency of said AC current is from about 30 to 90 cyclesper second,

the intensity of said field is from about 8 to about 12 microamps persquare inch,

the dielectric constant of said dielectric is at least 5 said dielectricbeing an isotropic material, and

said current creates a voltage gradient across said air space offrom to100 volts per mil.

3. An apparatus as claimed in claim 1 wherein:

said air space is about one-sixteenth inch thick,

said AC current has a sinusiodal wave form of less than 5 percent totalharmonic content,

said AC current is a 60 cycles per second current,

the intensity of said field is about 10 microamps per square inch,

the dielectric constant of said dielectric is at least 5,

said dielectric is an isotropic material, and

said current creates a voltage gradient across said air space of about95 volts per mil.

4. A process for treating a gas so as to neutralize electric chargeswhich comprises:

passing a gas to be treated through an air space between two electrodesseparated by a dielectric and said air space while applying an ACcurrent to said electrodes so as to create a field within said air spacehaving an intensity of at least 8 microamps per square inch, said gasbeing passed through said space at a rate such that said gas is betweensaid electrodes within said field during a complete cycle of saidcurrent or an even multiple thereof.

5. A process as claimed in claim 4 wherein:

said air space is from one-thirty-second to three-sixteenths inch thick,

said AC,current has the sinusiodal wave form of less than 5 percenttotal harmonic,

the frequency of said AC current is from about 30 to cycles per second,

the intensity of said field is from about 8 to 12 microamps per squareinch,

said dielectric is an isotropic material,

said current creates a voltage gradient across said air space of from 80to 100 volts per mil.

6. A process as claimed in claim 4 wherein:

said air space is about one-sixteenth inch thick,

said AC current has a sinusiodal wave form of less than 5 percent totalharmonic content,

said AC current is a 60 cycles per second current,

the intensity of said field is about 10 microamps per square inch,

the dielectric constant of said dielectric is at least 5,

said dielectric is an isotropic material, and

said current creates a voltage gradient across said air space of aboutvolts per mil.

@3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 354 534 Dated April 4 1972 Inventor(s) Rona] d 3 Fischer It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the Abstract:, line 3, "changed" should be --charged--;

Column 3, line 4, "duct 38" should be --duc t 28--;

Column 6, line 57, "paltes should be --plates--;

Column 6, line 57, "lower" should be higher;

Column 6, line 58, "like" should be "life- Signed and sealed this 5thday of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents 22 53? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3 654 534 Dated April 4 1972 Inventor(s) Rona] d 5. Fl SChEl"It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

In tne Abstract, line 3, "changed" should be --charged--;

Column 3, line 4, "duct 38" should be --duct 28--;

Column 6, line 57, "paltes" should be "plates";

Column 6, line 57, "lower" should be --h1'gher;

Column 6, line 58, "like" should be "life" Signed and sealed this 5thday of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR ROBERT GOTTSCHALK Attesting Officer Commissioner ofPatents

1. An apparatus for treating a gas so as to neutralize electric charges,which apparatus comprises: treatment means including electrodesseparated by a dielectric and an air space, means for applying an ACcurrent at a power level sufficient to create a field between saidelectrodes in said air space having an intensity of at least 8 microampsper square inch, and means for moving a gas through said air space at arate such that the gas is moved between said electrodes so as to besubjected to said field for a complete cycle of said AC current or aneven multiple thereof.
 2. An apparatus as claimed in claim 1 wherein:said air space is from one thirty-second to three-sixteenths inch thick,said AC current has a sinusiodal wave form of less than 5 percent totalharmonic, the frequency of said AC current is from about 30 to 90 cyclesper second, the intensity of said field is from about 8 to about 12microamps per square inch, the dielectric constant of said dielectric isat least 5, said dielectric being an isotropic material, and saidcurrent creates a voltage gradient across said air space of from 80 to100 volts per mil.
 3. An apparatus as claimed in claim 1 wherein: saidair space is about one-sixteenth inch thick, said AC current has asinusiodal wave form of less than 5 percent total harmonic content, saidAC current is a 60 cycles per second current, the intensity of saidfield is about 10 microamps per square inch, the dielectric constant ofsaid dielectric is at least 5, said dielectric is an isotropic material,and said current creates a voltage gradient across said air space ofabout 95 volts per mil.
 4. A process for treating a gas so as toneutralize electric charges which comprises: passing a gas to Be treatedthrough an air space between two electrodes separated by a dielectricand said air space while applying an AC current to said electrodes so asto create a field within said air space having an intensity of at least8 microamps per square inch, said gas being passed through said space ata rate such that said gas is between said electrodes within said fieldduring a complete cycle of said current or an even multiple thereof. 5.A process as claimed in claim 4 wherein: said air space is fromone-thirty-second to three-sixteenths inch thick, said AC current hasthe sinusiodal wave form of less than 5 percent total harmonic, thefrequency of said AC current is from about 30 to 90 cycles per second,the intensity of said field is from about 8 to 12 microamps per squareinch, said dielectric is an isotropic material, said current creates avoltage gradient across said air space of from 80 to 100 volts per mil.6. A process as claimed in claim 4 wherein: said air space is aboutone-sixteenth inch thick, said AC current has a sinusiodal wave form ofless than 5 percent total harmonic content, said AC current is a 60cycles per second current, the intensity of said field is about 10microamps per square inch, the dielectric constant of said dielectric isat least 5, said dielectric is an isotropic material, and said currentcreates a voltage gradient across said air space of about 95 volts permil.